Pick a number from two columns and calculate - c++

Question

A given file contains pairs of <two-digit number, amount>. Then take a toss-up two-digit number (called X), and compute the win/loss amount. The win/loss rule is if the input number matches X, then it’s a win and the winning total is (amount * 70); otherwise, it’s a loss of (-amount).
For example: [ticket.txt]
09 10
13 15
25 21
If the toss-up number is 09, the win/loss amount of the ticket is (10 * 70 - 15 - 21)
If the toss-up number is 42, the win/loss amount of the ticket is (-10 - 15 - 21).
This is my beginner project. I stuck at calculating the win amount and lost amount.
This is my problem
#include <iostream>
#include <fstream>
using namespace std;
int line1[100]; // array that can hold 100 numbers for 1st column
int line2[100]; // array that can hold 100 numbers for 2nd column
int main()
{
int winNum, winAmount, lostAmount;
int num = 0; // num start at 0
ifstream inFile;
inFile.open("Ticket.txt"); //open File
if (inFile.fail())
{
cout << "Fail to open the file" << endl;
return 1;
}
cout << "Numbers from File: " << endl;
while (!inFile.eof()) // read File to end of file
{
inFile >> line1[num]; // read first column, the first column is the number that user choosing
inFile >> line2[num]; // read second column, the second column is the amount of money that user paying
cout << "\n" << line1[num] << "\t" << line2[num];
++num;
}
inFile.close();
cout << endl;
cout << "Enter the toss-up number: "; // enter the win number
cin >> winNum;
if (line1[num] == winNum)
{
winAmount = line2[num] * 70; // number user choose = win number, winAmount = winAmount * 70 - lostAmount
cout << winAmount;
}
else
{
lostAmount =- line2[num]; //number user choose != win number, the amount will be -lost amounts
cout << lostAmount;
}
cout << endl << endl;
system("pause");
return 0;
}

Answer 1

You can see result at the end of the code
#include <iostream>
#include <fstream>
using namespace std;
int line1[100]; // array that can hold 100 numbers for 1st column
int line2[100]; // array that can hold 100 numbers for 2nd column
int main()
{
int winNum, winAmount = 0, lostAmount = 0, result = 0;
int num = 0; // num start at 0
ifstream inFile;
ifstream inFile2;
int rowNumber = 0;
string line;
inFile.open("Ticket.txt"); //open File
inFile2.open("Ticket.txt");
if (inFile.fail())
{
cout << "Fail to open the file" << endl;
return 1;
}
while (getline(inFile2, line))
++rowNumber;
cout << "Number of lines in text file: " << rowNumber << "\n";
int myArray[rowNumber][2];
for(int i = 0; i < rowNumber; i++)
for(int j = 0; j < 2; j++)
inFile >> myArray[i][j];
cout << "Numbers from File: " << endl;
for(int i = 0; i < rowNumber; i++)
{
for(int j = 0; j < 2; j++)
{
cout << myArray[i][j] << " ";
}
cout << "\n";
}
cout << endl;
cout << "Enter the toss-up number: "; // enter the win number
cin >> winNum;
for(int i = 0; i< rowNumber; i++)
{
if (myArray[i][0] == winNum)
{
winAmount = myArray[i][1] * 70; // number user choose = win number, winAmount = winAmount * 70 - lostAmount
}
else
{
lostAmount = lostAmount + myArray[i][1]; //number user choose != win number, the amount will be -lost amounts
}
}
result = winAmount - lostAmount;
cout << result;
cout << endl << endl;
system("pause");
return 0;
}

Answer 2

When you test line1[num] == winNum (and all the operations carried out after that) you're using the value of num that you modified with ++num;, this means you're working with empty or not meaningful values for both line1 and line2. For example, if the 3 rows of values showed in your "ticket.txt" are used, they are stored in postions 0, 1 and 2 of the arrays, while the num has a value of 4 at the end.
If I understood what you are trying to achieve, you should put the if-else statement in a for loop that goes from 0 to num, and then every operation on line1 and line2 should be done with the looping variable as an index.
Also, move the cout just after the loop if you want only total amounts to be displayed.